| Company Name | Company Location | Company Type | Most Recent Production | |
|---|---|---|---|---|
| 1 | O'Brien Energy Resources Corp | Portsmouth, NH 03801 | Oil & Gas Operator | Oct 2025 |
| 2 | Oedekoven Water & Hot Oil | Recluse, WY 82725 | Oil & Gas Operator | Sep 2025 |
| 3 | Okt Petroleum Company Inc | Oklahoma City, OK 73118-7425 | Oil & Gas Operator | Oct 2013 |
| 4 | Olympic Exploration Inc | Denver, CO 80202 | Oil & Gas Operator | Jul 2004 |
| 5 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 6 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Oct 2025 |